Projector



Dec. 14, 1937.

1.. J. ANDRES 2,101,890

PROJECTOR Filed May 14, 1934 2 Sheets-Sheet l INVENTOR.

ATTORNEY.

L. J. ANDRES Dec. 14, 1937.

PROJECTOR Filed May 14, 1934 2 Sheets-Sheet 2 o M a g f 0 W M H 9% QT w g a w Patented Dec. 14, 1937 8% UNITED STATES PATENT OFFWE PROJECTOR Lloyd J. Andres, Grand Rapids, Mich., assignor to Automatic Instrument Company, a corporation of Michigan Application May 14, 1934, Serial No. 725,470

6 Claims. (CI. 8817) This invention relates to motion picture and Fig. 3 is a straight line diagram of the consound picture projectors; and more particularly trol circuits. to the provision of safety means therefor. As shown in Fig. 1, the projector comprises a Objects of this invention are to provide a probase 3 on which is mounted a projector housing 4;

5 jector for handling celluloid film, which is simple a driving motor 5; and a starting switch mechaand safe to operate and especially fitted for nism box 6, on which is mounted. a lamp housing schools, lecture work, and the like. 1, containing a projector lamp 8. A fan 9 is A main fire hazard in such apparatus) arises provided for cooling the lamp by circulating air from the liability of the film being ignited by the through the housing l.

10 heat of the projector lamp. Under normal op- A starting button l0 and a stop button ll pro- 10 erating conditions means may be provided for ject from the box 8; and the motor is connected protecting the film from the heat when the film by a belt l2 to a main drive fly wheel pulley I3, is moving rapidly through the light beam; but mounted on a sound drive sprocket wheel shaft if the film stops moving for any reason, it is apt I4 in the projector housing. The pulley I3 is to be quickly damaged or ignited. connected by a belt l5 for driving a take-off reel 15 Accordingly, in this invention, means are proit which is contained in a housing or casing l'l vided for shutting off the lamp in case the movemounted on the front of the projector housing. ment of the film is retarded by failure in the The film F is drawn out of the roll casing l3 mechanical driving parts, such as abnormal fricand into the housing l by positively driven tion in the bearings, failure of the driving mechasprocket wheels I9; through the aperture plate 20 nism, a burnt out or defective motor, belt failure, 20 by the intermittent drive pulleys 2i through and the like. Also means are provided for stopa loop by positively driven sprockets 22; and over ping the motor and opening the lamp circuit in tension sprockets 23 and a sound take-off apercase the film breaks. ture plate 24, by constantly driven sprockets 25 25 The latter means is also effective for stopping mounted on the shaft M. Then, from the sound 25 the machine when the film is exhausted. Andrive sprockets, the film passes over a pair of other object is to facilitate the Ire-threading of p i iv ly v n hold-back sprockets B; and is the film, a lamp being provided which is autopulled out, over guide rollers 2'1, mounted in the matically lighted by the safety stop means to outlet slot 28 to the housing ll, and wound up on 80 illuminate the film track. the frictionally driven take-off reel 46. 30

Other objects are to provide a starting switch Referring to the cross section of the lower mechanism which will not remain closed unless portion of the projector 2. wn in and until the machine reaches the running speed p g finger Safety Switch is u d n and the operator cannot leave the machine operthe under e Of the p portion of the b e as ating without all conditions being correct. d a sp l f d plunger 3i is da y mounted as Another object is to provide such a mechanism in a casing 32 Which is fiXedly mounted on the in which no relays are energized while the ma- Wall Of the projector housing The plunger chine is in operation so that there will be no easing is p at the hhttehl and projects threugh interference with the sound reproduction when the adjacent Walls Of the housing d base, SO

40 alter tin u t i d, that, when the plunger is depressed, it presses 40 other objects and advantages 1 become the fingers of the switch 39 into contact and thus parent in the following description, taken with closes the switch reference to the accompanying drawings, in An arm 33 is provided which is pivotally mountwhich the invention is shown incorporated in a on the back W of the housing i is posi' Sound picture projector such as is disclosedm my tioned so that its movable end 33a will rest on l a and depress the plunger 3i. This arm carries a 512:2}: 22 1322 11 oller 34 which rests on the free stretch of the film between the sprockets 26 and the guide rollfully.shown. andfiescltlbed' ers 21 whereby the arm 33 is maintained in a 1 1s slde eevatlon of the prolfictor raised position out of contact with the plunger 50 wlth m P the Poncealed Parts of partlcular 3i while the machine is running and the film is interest lndlcated 1n broken hnesunder tension, the arm being allowed to drop F 2 is a diagram showing parts and p down and close the switch so when the film tions of t e machine housing in Section, d the breaks, runs out, or otherwise loses its tension,

electrical mechanism and circuits therefor. as by failure of the belt I5. 55

Leads from one side of the motor 5, the proiection lamp 8 and the cooling fan 9 are connected to a power lead wire 36 which is connccted to one of a pair of power lines 35 and 36, through a suitable double pole plug-in or knife switch 3'1. The opposite power line is connected through the switch 3? to a power lead 33 which runs to a binding post IV, and hence through a flexible wire 39, to a contact finger lil. Connected across the power leads 3d and 38, is a transformer ll for supplying low voltage current to excite the sound take 011 lamp 42 and for operating a relay 53.

The starting switch comprises an insulating switch block ed which is rotatably mounted on a suitable base did, on which is fixedly mounted a guide bracket '15, in which the push buttons l6 and l l are slidably mounted, and the frame 46 of the relay 53. Binding posts I, II, III, and the post IV, are fixedly mounted on the switch base member 3 3a; and a weighted trigger d! is rotatably mounted on the base and situated below the relay frame.

Binding post I is connected by wire 48 to one side of the relay winding; and the binding post II is provided with a stationary contact point d9, in cooperative relation with a relay switch contact finger B which is mounted on one side of the switch block 14 and connected by a flexible wire 5! to the opposite terminal of the relay :33. The binding post III is joined by wire 52 and branch wires 53 and 54 to the open terminals of the lamp 8, fan 9, and motor 5; then tins post has a stationary contact member 55 which cooperates with the switch finger 45 this finger being mounted on the block 44 on its side opposite the finger 59. Thus rotating the switch arm block 34, by depressing the starting button lil, closes the motor, lamp, and fan circuits; and also closes the relay switch which comprises the contact 49 and finger 5d, the finger 59 being lengthened so that it remains in contact after the motor switch finger all when the switch arm block id returns to open position.

In running condition the switch block M- is locked in closed position by means of a latch 56 which is engaged by a hook 5?, attached to the lower end of the block 3%; and the block is urged to rotate into open position by a spring 55 which is extended between the hook member 5? and the bracket To open the switch at will, the operator depresses the stop button I l, and this rotates the trigger i! into contact with and to raise and disengage the latch from the hook. The

latch 56 is rotatably mounted on the relay frame and is urged to rotate away from the relay pole 59 by a spring 68. A stop shoulder 45! is provided on the latch member which abuts against the relay frame and limits its outward movement.

One finger of the safety switch 33 is joined by the wire 62 to one side of the secondary E53 of the transformer ll; and the other finger of the switch 39 is connected by wire 64 to the binding post I, and hence to the relay 53 by wire 38.

Thus when the switch St is closed while the starting switch is in closed position, the relay is energized to attract and release the latch and allow the main switch to open, under the action of the spring 58.

This also lights a threading lamp 65 which is included in a connection 65a which extends from wire (i i to wire 6 .5 so that the lamp is automatically lighted to illuminate the interior of the housing for rethreading the film when the switch 36 is closed.

For opening the projection lamp and motor circuits when the speed of the film falls below the running speed, I provide a governor operated safety switch tl' comprising two insulated contact fingers, 68 and 69, mounted on the wall of the housing 4, and a contact ring Iii which is slidably mounted on the shaft H of the shutter ?2. The shutter is mounted on the outer surface of the rear wall of the housing, and is connected by the train of gearing to the driving pulley it, as described in particular in said application. The gear train also includes means for driving the sprockets, as mentioned; and the shutter is at the end of the train. Accordingly the shutter is the first to be afiected by failure in the drive.

A pair of governor weight arms E i are pivotally mounted on the hub '95 of the shutter; and the ring it is rotatably mounted on and insulated from a sleeve ll which is slidably mounted on the shutter shaft; and the sleeve is urged to move the ring into contact with the fingers 68 and E9, to close the switch, by a compressed spring it. The rear end of the sleeve ll is provided with a circular flange 79 which engages behind hooked portions of the governor weights. Therefore, when the m'acifine is running and the shutter r tating at the correct running speed,

- the weights pull the sleeve out against the action of the spring it and move the contact ring away from the fingers, and thus open the switch 6?.

The finger E3 is joined by wire St to the relay connection wire 65; and the finger E9 is connected by wire 82 to the transformer lead 62.

Hence the switch 6? is normally closed, and the relay will remain energized to prevent locking the starting switch until the running speed is reached.

To review the operations, the power leads 34 and 38 being connected to the power supply line, the film is threaded and the starter button it is depressed. This rotates the switch block 64 into closed position against the action of the spring 58. Before the latch becomes engaged with the hook 57, contact is made between the relay switch finger 5B and the contact to energize the relay 53, through the following circuit,-From transformer secondary 33; wire binding post II; contact 49; finger 5d; flexible wire 5! relay 43; wire 58; binding post I; wires 6:? and ill; through the closed switch 5? and wire 32 to the opposite side of the transformer. This causes the relay to attract and raise the latch 55, and the button 98 must be held depressed until the film is traveling at operating speed at which the governor opens the switch M.

The lamp 55 is excited through the switch 6'! until this switch is opened. Accordingly the lamp gives an indication as to when the running speed is reached and the button may be released.

As soon as the film is under tension the weight arm 33 is lifted and the switch 3i allowed to open. This will occur as soon as the film starts in motion, and the governor finally determines the time for de-energizing the relay and permitting the latch to drop and lock the switch block 44 in closed position.

Accordingly with the machine operating under normal running conditions both safety relay switches 61! and 3d are maintained in open condition. Then if the film breaks or runs out, with the machine running at full speed, the weight arm falls and the switch 38 is closed to energize the relay and release the latch, opening the main switch, and relighting the lamp 65.

In case the operator desires to discontinue the operation of the machine before the end of the film is reached, he depresses the stop button. This rotates the trigger 41 to lift the latch and disengage it from the hook 51.

Manifestly, by the use of this invention, the projector lamp circuit is opened at once when the speed of the film is retarded from mechanical trouble, by the governor; and in case the film breaks, by the weight arm 33; the operator is unable to get the machine started to running by itself unless all conditions are correct; a visible signal is given of subnormal operation; the machine is stopped if the film is not traveling properly through the housing; and the rethreading is facilitated by the automatic lighting of the threading lamp.

Having thus described my invention, I claim:

1. In a motion picture machine having a film driving motor and a projector lamp, an unlock ing relay, manually operable switch means for energizing said three elements, automatic means for locking said means in closed position and unlocking it, a governor operated by the motor, a film safety switch, a film threading lamp connected in parallel with the relay and lighted when the said switch means is closed, and means operated by the governor for maintaining the relay de-energized and ineffective and the film threading lamp unlighted at the operating speed unless the film safety switch is closed.

2. In a motion picture machine having a main circuit including a film driving motor and projection lamp, a pivotally mounted block having a contact finger for energizing the main circuit and having a relay contact finger, a spring for urging the block to rotate and move the contact fingers into open position, a push button for moving the block to closed contact position and for holding it in closed position until the motor attains the normal speed, a latch for holding the block in closed position, a relay energized by the relay contact finger, means controlled by the machine for de-energizing the relay under normal operation conditions, and a push button for manually releasing the latch to stop the machine at will.

3. In a motion picture machine, starting means comprising a double switch having a main contact for operating the machine and having a relay contact, a spring for opening the switch, manually operable means for closing the switch to start the machine and for holding the switch closed until the machine attains normal speed, a latch for holding the switch closed, a relay for releasing the latch, the relay being energized through the relay contact of the switch, safety means operated by the machine to de-energize the relay when and while the machine is in normal operating condition, and manually operable means for releasing the latch to stop the machine at will.

4. In a motion picture machine, a spring opened main switch, a push button for moving the switch to and holding it in closed position to start the machine into operation, a latch for holding the switch closed, a relay for releasing the latch, a safety switch maintained in open position by the machine under normal operating conditions and allowed to close under subnormal conditions, a signal lamp within the machine which is automatically lighted to indicate the subnormal condition when the safety switch is closed, the relay being connected in series through the main switch and the safety switch, and a push button for releasing the latch to open the main switch at will.

5. In a motion picture machine having a film driving motor circuit and a projector lamp circuit, a manual starting switch for energizing said circuits, a latch for locking the switch in closed position, a relay for releasing the latch, a circuit for the relay including the starting switch, a governor operated by the motor having a switch normally closed in series with the relay circuit, a film tensioning means having a switch normally open but closed when the film tension fails, in a circuit parallel with the governor circuit, and a film threading lamp in a circuit in parallel with the relay circuit and these two circuits in series 5 with the governor switch circuit and film tension switch circuit in parallel so that the threading lamp is lighted when the relay is energized either by the governor or by the film tensioning device.

6. In a motion picture machine, the combination with means for driving the film, a governor driven by said means, a projection lamp having a circuit, a manually operable switch for said circuit, a switch releasing relay, the relay and said switch being in a series circuit, a normally closed switch operated by the governor to deenergize the relay while the film is moving at a running speed, and a film threading lamp having a circuit in parallel with the circuit in which the manually operable switch and the relay are in series, and these parallel circuits being in series with the governor switch to light the threading lamp.

LLOYD J. ANDRES. 

